Sardana Streams

Sardana data streaming infrastucture. Comprises:

• redis based sardana scan recorder
• Client recorders:
  • generic scan stream client (library)
  • SPEC recorder daemon
  • HDF5 recorder daemon
  • Scan GUI

Installation

From within your favorite python environment:

$ pip install sardana-streams

Usage

The name acme used in the following examples represents a fictional corporation that features prominently in the Road Runner cartoons.

Configuration

Activate sardana redis recorder:

• Put the installation directory where the sardana_streams/recorder resides in RecorderPath tango property of the MacroServer. (ex: /usr/local/lib/python3.5/dist-packages/sardana_streams/recorder)
• From spock:
  • activate the recorder with: senv DataRecorder "['RedisRecorder']"
  • configure the recorder with senv RedisRecorder "{'host': 'acme.org', 'port': 7379, 'db': 1}" (replace host, port and db with your own)

The RedisRecorder env can be a string or a dictionary identifying the Redis database.

In case a string is given, it recognizes the same format url argument from redis.from_url().

In case a dict is given it recognizes the same keyword arguments as redis.from_url() plus:

• TTL: scan time to live in seconds (defaults to one week)
• key_prefix: scan key prefix (defaults to <macro server name>:sardana:scan)

Example

Here is a simple example of a client which simply listens to scan events and prints them on screen:

import contextlib

import redis
from sardana_streams.client import ScanStream

db = redis.from_url('redis://acme.org:7379/1')
prefix = "acme:sardana:scan"
stream = ScanStream(db, prefix)
with contextlib.closing(stream):
    for event in stream:
        print(event)